Gyratory crushers, such as cone crushers and spindle crushers, generally comprise an outer shell which is fixedly connected to a body, and an inner shell which is arranged radially inside said outer shell. The inner shell is connected to an internal shaft member for executing a gyratory movement. Between the two shells a crushing chamber is defined, in which crushing of a material is carried out as the inner shell moves.
It is common for the shaft member to be vertically adjustable for changing an axial distance between the two shells. As a result, the particle size of the crushed material can be adjusted. The vertical adjustability is usually achieved by the shaft member being supported by a piston member which is vertically adjustable in a cylinder member.
The shaft member, which must be rotatable relative to the piston member, is mounted in a thrust bearing which is arranged between the shaft member and the piston member and to which a medium for promoting the function of the bearing, suchas a lubricant or hydraulic fluid, must be supplied during operation of the crusher.
The medium is supplied to the thrust bearing from a tank via a transport duct extending through the cylinder member and the piston member. In the transition between the cylinder member and the piston member, the duct is formed on the side of the cylinder member as a small opening and on the side of the piston member as an area of a large extent in the axial direction, thus allowing the medium to be transferred in each individual position of the piston. It is then necessary for the axial length of the area of the duct in the piston member adjacent to the cylinder member to be at least as great as the length of stroke of the piston member, i.e. the distance between the top and bottom position of the piston member.
A problem in prior-art gyratory crushers is that they are large and unwieldy, and especially they need a relatively large space in the vertical direction. This causes difficulties and a limited possibility of choosing the position of such crushers. Particular difficulties exist in mobile crushers.